There are numerous prior art meter runs having orifice plates mounted therein which are used for measuring the flow of gases and liquids. For example, out in the oil patch, when a new production field is first opened, the meter runs are of very large diameter, as for example 12 inches i.d., that employ a large orifice plate having a large bore formed therein, for example a 4 inch diameter bore, which provides an acceptable beta ratio. As the years go by and the production diminishes, the large flow lines are no longer needed. However, since the large flow lines are already installed, it is uneconomical to substitute a small flow line therefor. Furthermore, it is always possible that additional lateral lines will someday be incorporated into and augment the original flow line, so it is often advantageous to leave the large line installed.
However, the large 12 inch meter run presents a flow measuring problem because the orifice plate associated therewith must be provided with a progressively smaller orifice, or flow passageway, as the flow through the meter run diminishes over the years. The ratio of the orifice located along the central axis of the orifice plate to the diameter of the meter run is called the beta ratio. The beta ratio must be within a predetermined limit in order for reliable measurement of the fluid flowing therethrough to be achieved.
It is quite expensive to replace a 12 inch meter run with a 4 inch meter run, for example. Instead, those skilled in the art have discovered that a large existing meter run can be effectively reduced to any predetermined smaller size by incorporating a meter tube insert therewithin. The meter tube insert is usually telescopingly positioned within the old meter run, and when the reduced diameter orifice plate is incorporated therewith, the beta ratio is brought into a more satisfactory range of values.
It is known to install a reduced diameter tube within an existing flow line, as evidenced by the following U.S. patents: Dodge No. 1,266,428; Mapelsden No. 1,698,314; and Carbone No. 2,942,465. However, none of these patents disclose a meter tube insert which is installed within an existing meter run in order to achieve a more favorable beta ratio.
There are available various different meter tube fittings for holding an orifice plate within a meter run, as evidenced by the U.S. patents to Haldeman No. 1,631,264; Fisher No. 1,575,259; Engel No. 1,980,672; Daniel No. 2,407,951; Smith No. 1,904,333; and Worthen No. 2,252,337. Some of these devices employ simple confronting type flanges, while others are more complex for enabling the orifice plate to more easily be assembled in sealed relationship between the confronting faces of the fitting cavity. Some of the above recited patents teach that the orifice plate can be held within some sort of fixture. Gall, et al U.S. Pat. No. 4,442,339; Scott U.S. Pat. No. 4,393,722; and Wetherill U.S. Pat. No. 1,731,404 also teach that an orifice plate can be mounted within a fixture to thereby simplify the task of changing or inspecting the orifice plate.
Furthermore, Applicant has reason to believe that public disclosure has been made of a meter tube insert of a type wherein a commercially available meter tube fitting of a meter run is sized down to a more suitable diameter in order to improve the beta ratio. However, in this particular prior art combination of a meter tube fitting and insert, difficulty has been experienced in properly installing the orifice plate and later retrieving the orifice plate from the fitting and insert. The present invention disclaims the meter tube fitting and the meter tube insert, and accordingly, the subject of the present invention embraces an adaptor apparatus by which an orifice plate can be concurrently mounted in sealed relationship respective to the confronting faces of both a meter tube fitting and a meter tube insert.